Line Lock with Drum Brakes ?

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1969GTS340

1969GTS340

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Hey A Body racers. I have drums on all fours and took the car to the track for the first time this weekend. My line lock did not hold the car at all during the burn out. Foot braked at the starting line worked good. I'm hoping it only needs a tighter adjustment on the front shoes to give the added holding power. Or possibly the proportioning valve need tweeking? Anyone else have this set up with good results ? Thanks.
 
The line lock locks up any pressure that your foot applied, you sure you aren't just sliding the front tires?
 
I'm sure they are rolling. I had spotters at the box and we tested in the pit area. They just roll.
 
Gotta ask the stupid question so forgive me. Are the shoes on the right way? Long shoe in the rear short shoe in the front?
 
I have drums all around on my 67 A100. OEM 11x2.5” drums on fronts w/line lock. The amount of bite is determined by how hard I press on the brake pedal. It’s all in your left leg. First time at the track is always a learning experience, soon it will be automatic and then it’s on to getting the burnout right.
 
RustyRatRod said:
Gotta ask the stupid question so forgive me. Are the shoes on the right way? Long shoe in the rear short shoe in the front?
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I will check to confirm that. Everything brake wise is brand new except for the backing plates. I'll pull the drums to check. I'm open to any possibilities, so thank you for that.
 
1969GTS340 said:
I will check to confirm that. Everything brake wise is brand new except for the backing plates. I'll pull the drums to check. I'm open to any possibilities, so thank you for that.
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You bet. I wasn't trying to be smart......you just never know. As many hundreds of drum brake jobs as I've done through the years, I've installed them backwards before. So there's that. LOL
 
12many said:
I have drums all around on my 67 A100. OEM 11x2.5” drums on fronts w/line lock. The amount of bite is determined by how hard I press on the brake pedal. It’s all in your left leg.
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I pumped them 3 times and held with both legs/feet. The peddle feels firm. I'm guessing your line lock holds?
 
1969GTS340 said:
I pumped them 3 times and held with both legs/feet. The peddle feels firm. I'm guessing your line lock holds?
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I never have to pump, just press hard on the pedal with my left foot and hit the switch and do my burnout.
You might need to bleed your brakes, inspect etc perhaps?
 
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If they're really new, low mileage, without the shoes "arced" to match the drums, might take a few hundred miles for them to "seat" .
 
12many said:
I never have to pump. I roll up and spin the rears through the water, pull up a bit and then stop, pressing hard on the pedal with my left foot hard and hit the switch and do my burnout.
You might need to bleed your brakes, inspect etc perhaps?
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Thanks for that. I'll add that to my list of troubleshooting.
 
inertia said:
If they're really new, low mileage, without the shoes "arced" to match the drums, might take a few hundred miles for them to "seat" .
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That's an excellent point.
 
inertia said:
If they're really new, low mileage, without the shoes "arced" to match the drums, might take a few hundred miles for them to "seat" .
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Ouch.... if thats the case, I'll need to make over 1000 passes down the track to break them in.
 
1969GTS340 said:
Thanks for that. I'll add that to my list of troubleshooting.
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Once you verify, possibly sort things you should have no problems. Only thing left is staying focused and getting your routine down and remembering to press HARD every time.
 
1969GTS340 said:
Ouch.... if thats the case, I'll need to make over 1000 passes down the track to break them in.
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I don't think so. Have you burnished them? Get up to like 60 and HARD brake down to 30 several times. That should do it.
 
If it were mine, I'd re-bleed the brakes, pull front drums, check shoe contact area. Find an old arcing machine if contact suggests that's the prob.
Drag the brakes down the return lane a few times.
Good luck .
 
RustyRatRod said:
I don't think so. Have you burnished them? Get up to like 60 and HARD brake down to 30 several times. That should do it.
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Through time trials and eliminations, they've been burnished from 90ish down to 15 a dozen times.
 
I’ve done this on drum brake motorcycles: cut strips of sandpaper, 120ish or so, spray adhesived the backsides of the sandpaper and completely lined the drums. Assemble and Spin the wheel and gently and progressively applied the brakes. Actually works great. A ***** to remove and clean the glue off! Haven’t tried on a car but if you had a helper and were feeling experimental.....
 
Just have to ask...

Are you using the line lock to prevent pressure to the rear brakes

Or

To hold pressure in the front brakes?
 
Been there done this…lol. First, primary shoes on both sides, front and rear of the brake assemblies.

Second, brake pressure gauge and figure out by pumping the brakes prior to line lock engagement what works best.

Or…in lieu of the second above, adjust the proportioning valve.

This is of course assuming that all brake components are fresh and functioning as intended.

You can also consider a different master cylinder for increased piston area.
 
1969GTS340 said:
As crazy as that.would be, I'll check it lol
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Make sure in side is coming from master cylinder out is to BOTH front brakes. The back brakes should not be in this hookup, at one time I used two locks, one for front and one for back. Poor mans trans brake with two step.
 
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